Nicotinamide, (/ˌnɪkəˈtɪnəmaɪd/) also known as niacinamide,[2][3]NAA, and nicotinic amide, is the amide of nicotinic acid (vitamin B3 / niacin).[2][3] Nicotinamide is a water-soluble vitamin and is part of the vitamin B group. Nicotinic acid, also known as niacin, is converted to nicotinamide in vivo, and, though the two are identical in their vitamin functions, nicotinamide does not have the same pharmacological and toxic effects of niacin, which occur incidental to niacin's conversion. Thus nicotinamide does not reduce cholesterol or cause flushing,[4] although nicotinamide may be toxic to the liver at doses exceeding 3 g/day for adults.[5] In cells, niacin is incorporated into nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), although the pathways for nicotinic acid amide and nicotinic acid are very similar. NAD+ and NADP+ are coenzymes in a wide variety of enzymatic oxidation-reduction reactions.[6] Commercial production of niacin and niacinamide (several thousand tons annually) is by hydrolysis or aminolysis of 3-cyanopyridine (nicotinonitrile).[7]

Nicotinamide has anti-inflammatory actions. These may be of benefit to patients with inflammatory skin conditions.[8] These conditions include acne vulgaris, and the compound can suppress antigen-induced, lymphocytic transformation and inhibit 3',5'-cyclic-AMP phosphodiesterase. Nicotinamide has demonstrated the ability to block the inflammatory actions of iodides known to cause or exacerbate inflammatory acne.

NicAzel, Azerizin, and Nicomide are the names of oral acne medications that include nicotinamide as a predominant ingredient, based on this area of research. Nicotinamide is also used topically as a 4% or 5% gel or cream - as effective as topical 1% clindamycin (8-week double-blind trial) performed at the New York University College of Medicine.[9] Unlike topical Erythromycin or Clindamycin it does not lead to bacterial resistance to these antibiotics, when used to treat inflammatory acne. Nicotinamide acne treatment is also available as Nicotinamide pads and cream.

A 2013 double blinded clinical trial in the International Journal of Dermatology showed that topical 4% nicotinamide gel was as effective as 1% clindamycin gel in the treatment of moderate inflammatory acne vulgaris.[10] The study also showed that clindamycin worked better in people with non-oily (normal, dry) skin types, while nicotinamide worked better in people with oily skin types.

Nicotinamide increases the biosynthesis of ceramides in human keratinocytes in vitro and improves the epidermal permeability barrier in vivo.[11] The application of 2% topical nicotinamide for 2 and 4 weeks has been found to be effective in lowering the sebum excretion rate in study participants.[12] Nictotinamide has been shown to prevent Propionibacterium acnes-induced activation of toll-like receptor (TLR)-2, which ultimately results in the down-regulation of pro-inflammatory IL-8 production.[13] These are some of the possible mechanisms by which nicotinamide may help in acne vulgaris.

A phase III double-blinded, randomized, and controlled trial investigating possible roles of nicotinamide in the prevention of non-melanoma skin cancer was performed by the same researchers who carried out the phase II trial referenced above. The trial enrolled 386 patients, who had at least two non-melanoma skin cancers in the last 5 years. The rates of new non-melanoma skin cancer diagnosed during the study period were 23% lower in the nicotinamide group (500 mg twice a day) compared to the placebo group. The study also showed that those in the nicotinamide group, AKs were reduced by 11% at 3 months, 20% at nine months, and 13% at 12 months compared to the placebo group. There was no added effect beyond the 12-month treatment period, suggesting that continuous dosing is necessary to see benefit. There were no differences between the groups with regard to adverse effects.[15]

Nicotinamide may aid chemotherapy-and radiation therapy by acting as a sensitizing agent/cancer-growth-promoter resulting in enhanced blood flow to tumors and thus increased oxygen supply to tumors, thereby reducing tumor hypoxia. Niacinamide also inhibits poly(ADP-ribose) polymerases (PARP-1), enzymes involved in the rejoining of DNA strand breaks induced by radiation or chemotherapy.[20] PARP-1 appears to be an important target for triple negative breast cancers because the cells are sensitive to inhibition of PARP-1.[21] Niacinamide is also used by some patients in combination with "intravenous vitamin C" treatment for cancer.[22] Niacinamide has also been reported as preventing suppression of the immune system caused by UVA and UVB radiation (so it could potentially be added to sunscreen).[23]

In an open label randomized trial with twenty patients having bullous pemphigoid (BP), tetracycline combined with oral nictotinamide was shown to be as effective as prednisone in treating BP.[24] There are several case reports which support the efficacy of this therapy.[25] It is considered to be a steroid sparing regimen. Recommended dosing is tetracycline 500 mg four times daily or doxycycline100mg twice daily or minocycline 100 mg twice daily, combined with nicotinamide 500 mg four times daily.[26]

Nicotinamide lacks the vasodilator, gastrointestinal, hepatic, and hypolipidemic actions of nicotinic acid. As such, nicotinamide has not been shown to produce the flushing, itching, and burning sensations of the skin as is commonly seen when large doses of nicotinic acid are administered orally. High-dose nicotinamide should still, however, be considered as a drug with toxic potential at adult doses in excess of 3 g/day and unsupervised use should be discouraged.[5] Overall, however, it rarely causes side effects, and is considered generally safe as a food additive, and as a component in cosmetics and medication.[35]

^ abRolfe HM (2014). "A review of nicotinamide: treatment of skin diseases and potential side effects". Journal of Cosmetic Dermatology. 13 (4): 324–8. doi:10.1111/jocd.12119. PMID25399625. Nicotinamide, also known as niacinamide, is the amide form of vitamin B3.

^ abMacKay D, Hathcock J, Guarneri E (2012). "Niacin: chemical forms, bioavailability, and health effects"(PDF). Nutrition Reviews. 70 (6): 357–66. doi:10.1111/j.1753-4887.2012.00479.x. PMID22646128. Retrieved 2015-10-25. The forms of niacin available in the marketplace include unbound niacin, or free nicotinic acid (NA); extended-release NA, a form of NA that is released gradually over a period of time; inositol hexanicotinate, six molecules of NA covalently bonded to one molecule of inositol; and nicotinamide, or niacinamide, the amide form of NA, which is readily bioavailable.